Warrior talent · row 5 of Protection, from level 30 (25 with Talented 5/5) · Physical

Improved Shield Wall

Reduces the cooldown of your Shield Wall ability by 5.5/11 min.

Game files · build 1.60.1.70245Read from the WoW Forever beta client, build 1.60.1.70245.

Compared with Classic

Classic tooltip

Increases the effect duration of your Shield Wall ability by 3 secs.

Data	Classic	Forever
effect 1 value	3000	-660000

What Blizzard said about Improved Shield Wall, each line checked against the files.

Matches the files
Improved Shield Wall: (Redesigned.) Now reduces the cooldown on Shield Wall by a large amount.
The files Classic added 3/5 sec duration; 70245 cuts Shield Wall's 15 min cooldown by 5.5/11 min (spell 12312).
Improved Shield Wall Shield Wall Class deep dives: Priest and Warrior

69876 Sep 16First beta build we archived. No changes in the client files since.